The Do Not Consume notice on the Mountainlodge Group Water Scheme remains in place but criteria for its lifting have been agreed.
The notice was put in place earlier this month after elevated levels of manganese and aluminium were found after testing.
In a statement this afternoon, Cavan County Council said reduced rainfall has led to an increase in the level of manganese in the raw water supply in the Mountainlodge Group Water Scheme.
It says the notice remains in place but the HSE and Council have agreed a set of markers that must be met before the notice is lifted.
It says preliminary investigations have found the high levels of aluminium and manganese in the raw water for the scheme do not appear to have been taking place over the long term or over a period not greater than four weeks.
The local authority says the most recent monitoring has indicated that water quality has returned to compliant levels but further testing is required the entire supply is marked compliant.
